Portable communications products, such as radios, are often powered off of rechargeable batteries. A battery can be charged based on a variety of parameters such as voltage, battery chemistry, rated capacity, and temperature for a particular battery. While positive and negative charge terminals are used for charging the battery and measuring the battery cell voltage, many batteries also include additional contacts for monitoring such parameters as temperature, rated battery capacity and chemistry type. Furthermore, the battery usually includes another set of separate positive and negative power contacts to interface the battery to the radio. The use of multiple contacts adds not only to the cost of the battery and charger but is often a source of intermittence due to misalignment and/or contact contamination.
Manufacturers of battery chargers have realized that the chargers can be made less sophisticated and less expensive if the battery provides some indication of how it should be recharged. One way for transferring battery information to the charger with fewer contacts is to produce a battery with a memory device. The memory device contains charge instructions and other recharge related data, such as rated capacity and chemistry. When the battery is coupled to the charger, the charger retrieves the information from the battery's memory and charges the battery accordingly. However, certain cell parameters, such as temperature, pressure, and voltage, are dynamic in that they can vary throughout the charge cycle and therefore do not lend themselves to being stored as a parameter in memory.
Accordingly, there is a need for an improved battery pack and charge system which can effectively monitor battery parameters including those parameters with dynamic characteristics while eliminating the need for separate contacts. It would be a further benefit to minimize the overall use of interface contacts in battery-to-charger systems and/or battery-to-radio systems where possible.